Add README.md for examples (grpc-ecosystem#645)

* Create README.md

Add a README.md file to help begginers to start more quickly. I think it may help.

* Update README.md

examples/README.md

@@ -0,0 +1,40 @@
+# One way to run the example
+
+```bash
+# Handle dependencies
+$ dep init
+```
+
+Follow the guides from this [README.md](./browser/README.md) to run the server and gateway.
+```bash
+# Make sure you are in the correct directory: 
+# $GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/examples
+$ cd examples/browser
+$ pwd
+
+# Install gulp
+$ npm install -g gulp-cli
+$ npm install
+$ gulp
+
+# Run
+$ gulp bower
+$ gulp backends
+```
+
+Then you can use curl or a browser to test:
+
+```bash
+# List all apis
+$ curl http://localhost:8080/swagger/echo_service.swagger.json
+
+# Visit the apis
+$ curl -XPOST http://localhost:8080/v1/example/echo/foo
+{"id":"foo"}
+
+$ curl  http://localhost:8080/v1/example/echo/foo/123
+{"id":"foo","num":"123"}
+
+```
+
+So you have visited the apis by HTTP successfully. You can also try other apis.